Pivot knob portion of a welding helmet



FIG. 1 is a perspective view, showing the new design for a pivot knob portion of a welding helmet;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view, the right side view being a mirror image thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a bottom view thereof.

The details shown in broken lines form no part of the claimed design. The surface shading is provided to illustrate contour only. 

The ornamental design for a pivot knob portion of a welding helmet, as shown and described. 